Borrelia miyamotoi Activates Human Dendritic Cells and Elicits T Cell Responses

Changes in the Transcriptome and Long Non-Coding RNAs but Not the Methylome Occur in Human Cells Exposed to Borrelia burgdorferi

Lyme disease, caused by infection with members of the Lyme borreliosis group of Borrelia spirochete bacteria, is increasing in frequency and distribution worldwide. Epigenetic interactions between the mammalian host, tick, and bacterial pathogen are poorly understood. In this study, high-throughput next-generation sequencing (NGS) allowed for the in vitro study of the transcriptome, non-coding RNAs, and methylome in human host cells in response to Borrelia burgdorferi infection. We tested the effect of the Borrelia burgdorferi strain B31 on a human primary cell line (HUVEC) and an immortalized cell line (HEK-293) for 72 h, a long-duration time that might allow for epigenetic responses in the exposed human host cells. Differential gene expression was detected in both cell models in response to B. burgdorferi. More differentially expressed genes were found in HUVECs compared to HEK-293 cells. Borrelia burgdorferi exposure significantly induced genes in the interferon, in addition to cytokine and other immune response signaling in HUVECs. In HEK-293 cells, pre-NOTCH processing in Golgi was significantly downregulated in Borrelia-exposed cells. Other significantly altered gene expressions were found in genes involved in the extracellular matrix. No significant global methylation changes were detected in HUVECs or HEK-293 cells exposed to B. burgdorferi; however, two long non-coding RNAs and a pseudogene were deregulated in response to B. burgdorferi in HUVECs, suggesting that other epigenetic mechanisms may be initiated by infection.

Acute Meningoencephalitis Associated with Borrelia miyamotoi, Minnesota, USA

Borrelia miyamotoi is an emerging tickborne pathogen that has been associated with central nervous system infections in immunocompromised patients, albeit infrequently. We describe a case-patient in Minnesota, USA, who had meningeal symptoms of 1 month duration. B. miyamotoi infection was diagnosed by Gram staining on cerebrospinal fluid and confirmed by sequencing.

Borrelia miyamotoi: A Comprehensive Review

Borrelia miyamotoi is an emerging tick-borne pathogen in the Northern Hemisphere and is the causative agent of Borrelia miyamotoi disease (BMD). Borrelia miyamotoi is vectored by the same hard-bodied ticks as Lyme disease Borrelia, yet phylogenetically groups with relapsing fever Borrelia, and thus, has been uniquely labeled a hard tick-borne relapsing fever Borrelia. Burgeoning research has uncovered new aspects of B. miyamotoi in human patients, nature, and the lab. Of particular interest are novel findings on disease pathology, prevalence, diagnostic methods, ecological maintenance, transmission, and genetic characteristics. Herein, we review recent literature on B. miyamotoi, discuss how findings adapt to current Borrelia doctrines, and briefly consider what remains unknown about B. miyamotoi.

NKG2D Enhances Double-Negative T Cell Regulation of B Cells

Numerous studies reported a small subpopulation of TCRαβ+CD4-CD8- (double-negative) T cells that exert regulatory functions in the peripheral lymphocyte population. However, the origin of these double-negative T (DNT) cells is controversial. Some researchers reported that DNT cells originated from the thymus, and others argued that these cells are derived from peripheral immune induction. We report a possible mechanism for the induction of nonregulatory CD4+ T cells to become regulatory double-negative T (iDNT) cells in vitro. We found that immature bone marrow dendritic cells (CD86+MHC-II- DCs), rather than mature DCs (CD86+MHC-II+), induced high levels of iDNT cells. The addition of an anti-MHC-II antibody to the CD86+MHC-II+ DC group significantly increased induction. These iDNT cells promoted B cell apoptosis and inhibited B cell proliferation and plasma cell formation. A subgroup of iDNT cells expressed NKG2D. Compared to NKG2D- iDNT cells, NKG2D+ iDNT cells released more granzyme B to enhance B cell regulation. This enhancement may function via NKG2D ligands expressed on B cells following lipopolysaccharide stimulation. These results demonstrate that MHC-II impedes induction, and iDNT cells may be MHC independent. NKG2D expression on iDNT cells enhanced the regulatory function of these cells. Our findings elucidate one possible mechanism of the induction of peripheral immune tolerance and provide a potential treatment for chronic allograft rejection in the future.